Method and apparatus for cooling a room

ABSTRACT

In order to cool a room, a cooling element fitted in the ceiling region is cooled to below the freezing point, preferably to about -40° C., during the cooling phases so that condensate forming thereon freezes immediately. During regeneration phases when the room is not in use, the cooling element is defrosted and the melted condensate is caught in a condensate tray beneath the cooling element and drained via a discharge. The great temperature difference between the room to be cooled and the cooling element also makes it possible to obtain a strong cooling effect with a small cooling element, especially by indirect radiation exchange between the room and the cooling element via an intermediate ceiling. In addition, the air in the room is dehumidified since water vapor is deposited on and bonded to the cooling element in the form of ice.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for cooling a room by radiant heatexchange and to an apparatus for carrying out the method.

2. Description of the Related Art

It is known (see for example H. Sokolean: "Kuhldeckentechnologie zurErreichung des bestmoglichen Raumkomforts", [Cooling-ceiling technologyfor achieving the best possible interior conditions], Architektur undTechnik August 1992, p. 49-53, B+L Verlags AG, Schlieren (Switzerland)),to cool rooms by means of cooling elements which are preferably arrangedin the ceiling area and through which usually there flows a heattransfer medium cooled in a central refrigerating unit. In this case,the cooling takes place by convective heat exchange of the coolingelement with the air in the room and in particular by direct radiationexchange of the same with the objects located in the room.

The cooling capacity of such cooling elements is limited by the factthat their surface temperature must not drop below the dew point, sinceotherwise condensate forms during the cooling phases, which usuallycoincide with the times during which the room is in use. Although it hasbeen proposed (WO-A-91/13 294) to cool below the dew point and to drainthe condensate produced away by means of condensate channels or trays,it must be assumed that the formation of condensate during use of theclimatically conditioned room is always problematical and undesired.

Also known (from DE-A-28 02 550) is a device for drying and cooling airin which the air is sucked by means of a fan over a cooling elementwhich is temporarily cooled below the freezing point and which is freedof deposited frost by heating during short regeneration phases. However,such devices are not suitable for use in a room to be climaticallyconditioned and would therefore require air to be transported by forcedconvection, which would have to cause undesired draughts.

Since the dew point at the usually prevailing atmospheric moisturelevels is around 12° C. to 15° C., if the formation of condensate is tobe avoided in the case of a conventional cooling element arranged in theroom to be cooled, the difference between the permissible temperature ofthe said element and the desired room temperature of about 22° C. isvery small and the cooling capacity which can be achieved iscorrespondingly modest. As a result, very large cooled surfaces arerequired, which entails comparatively high costs and has the effect ofrestricting interior design possibilities.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a remedy to the abovelimitations. The invention, as characterized in the claims, provides amethod for climatically conditioning rooms in which the temperature ofthe cooling element is no longer restricted by the dew point. Thefundamental idea here is to cool the cooling element during coolingphases, which coincide to a great extent with the times during which theclimatically conditioned room is in use, to such an extent thatcondensate deposited on the said element quickly turns to ice and, as aresult, no problematical condensation water is produced. Duringregeneration phases, which are generally chosen to be outside the timesof use, the frozen condensate is melted off and drained away in liquidform.

The advantages achieved by the invention are particularly associatedwith the fact that the temperature of the cooling element can be set aslow as desired. As a result, very high cooling capacities can beachieved even with small cooling surfaces, even if the heat exchangewith the room to be climatically conditioned takes place exclusively bymeans of radiation and little, if at all, free convection. This effectis further promoted by the fact that, in the infrared range, ice hasradiation properties very similar to those of a black body and the icingof the cooling element has an entirely favourable effect on the decisivedirect or indirect radiation exchange with objects in the climaticallyconditioned room. The cooling elements can consequently be kept smalland simple in construction, whereby, of course the costs are reduced andno longer play the previous restrictive role as a factor to be takeninto account in interior design.

In addition, another problem is solved, one which until now presenteddifficulties with generic methods of climatically conditioning rooms andcould only be dealt with by exchanging the air in the room, whichhowever, requires additional installations and entails the risk ofundesired draughts being produced.

In particular, if the room is being used for a considerable period oftime by a high concentration of people, the humidity of the air in theroom increases rapidly. This is perceived as unpleasant, and often leadsto the attempt to remedy the situation by opening the windows; thishowever in the summer months in particular, often further aggravates theproblem owing to the high humidity of the outside air. The highatmospheric humidity may finally result in, even with the coolingelements at a relatively high temperature, the risk of condensation andof the cooling system being switched off entirely by dew-point monitors.Consequently, the cooling is shut down at the very time it is neededmost urgently.

By contrast, in the case of the method according to the presentinvention, atmospheric moisture is bound on the cooling element by icingof the condensate. As a result, the air in the room remains dry, whichmakes conditions considerably more comfortable and does not allowdifficulties of the kind described previously to arise at all.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below with reference tofigures, which merely illustrate exemplary embodiments, in which:

FIG. 1 is a cross section through a room which is climaticallyconditioned by the method according to the present invention,

FIG. 2a is a plan view of a first embodiment of an apparatus accordingto the present invention for carrying out the method according to theinvention,

FIG. 2b is a cross-section along line B--B through the apparatus of FIG.2a,

FIG. 3a is a plan view of a second embodiment of an apparatus accordingto the present invention for carrying out the method according to theinvention,

FIG. 3b is a cross-section along line B--B through the apparatus of FIG.3a,

FIG. 4a is a plan view of a third embodiment of an apparatus accordingto the present invention for carrying out the method according to theinvention,

FIG. 4b is a cross-section along line B--B through the apparatus of FIG.4a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A room 1 to be climatically conditioned (FIG. 1) usually containsheat-emitting objects, such as people and equipment, which exchange heatwith a cooling apparatus through a perforated ceiling 2. The coolingapparatus includes at least one cooling element 3, which is connected bymeans of a feed line 4 and a draining line 5 directly or indirectly to arefrigerating unit 5. The cooling apparatus includes a condensate tray7, which is arranged vertically below the cooling element 3, is of aslightly larger surface area than the cooling element and has adischarge 8. The cooling apparatus is preferably arranged above theperforated ceiling 2. It is also possible, however, to integrate thecondensate tray 7 into the ceiling 2, for example in such a way that itreplaces a ceiling panel. Above the cooling apparatus, preferably about20-30 cm away from the cooling element, there is incorporated a ceilingor intermediate ceiling 9 of concrete or plaster.

During a cooling phase, the cooling element 3 is cooled below thefreezing point, to at least -5° C., but preferably much lower, forexample -40° C. Usually, condensate is then soon deposited on thecooling element, immediately turns to ice and is consequently bound tothe cooling element. The cooling of the room 1 takes place predominantlyby radiation exchange via the intermediate ceiling 9, which is intenselycooled by direct radiation exchange with the iced cooling element,since, in the infrared range, the ice cooling element is very similar toan ideal black body and absorbs very efficiently the radiation emanatingfrom the intermediate ceiling 9, whereas for its part, on account of itslow temperature, the iced cooling element radiates much less heattowards the intermediate ceiling 9.

On the other hand, the intermediate ceiling 9 exchanges heat radiationwith the room 1, in particular with any heat-emitting objects in it,through the perforated ceiling 2. It absorbs part of the heat radiationemanating from these objects and, on account of the lower temperature ofthe intermediate ceiling, it radiates less heat than it absorbs. Part ofthe radiation reaching the intermediate ceiling 9 is, of coursereflected and partly absorbed by the cooling element 3. The condensatetray 7 is also cooled by radiation exchange with the cooling element 3,and for its part, contributes to the cooling of the room 1 by radiationexchange with it. However, the temperature on the outside of thecondensate tray 7 must not fall below the dew point, since otherwisecondensate would form on its underside posing a potential problem tousers of the room. The heat exchange by radiation is indicated in FIG. 1by straight arrows.

In addition, convective heat exchange of the room 1 also occurs ofcourse, in particular with the intermediate ceiling 9 but also directlywith the cooling apparatus. In FIG. 1, this is indicated for the risinghot air by solid curved arrows and for the falling cold air by dashedcurved arrows. However, the convection plays only a secondary role.

Due to the great temperature difference between the cooling element 3and the room 1, which may well be 60° C., the cooling effect of theradiation exchange, which as known follows a T⁴ law, is very high. As aresult, an intense cooling effect can be achieved even with a smallcooling element 3. Moreover, the air in the room 1 always remainsrelatively dry, since excess atmospheric moisture precipitates on thecooling element 3 and turns to ice. In this way, the most comfortableroom conditions are established without further measures.

During a lengthy cooling phase, a relatively large amount of iceprecipitates on the cooling element and ultimately has to be thawed anddrained away during a regeneration phase, which is usually arranged tobe performed at a time during which the room 1 is not being used. It isusually sufficient for thawing to simply switch off the refrigeratingunit and to allow the ice deposited on the cooling element 3 to melt offby heat exchange with the surrounding atmosphere. It is also possible toperform a rapid regeneration by heating of the cooling element 3. Themelted-off water is cooled by the condensate tray 7 and drained away viathe discharge 8. After the ice has melted off completely, or possiblyeven only partially, the cooling apparatus is ready for use again.

According to a first embodiment of a cooling apparatus (FIGS. 2a, b),the cooling element 3 is designed as an evaporator made of sheet steel,which is connected via a heat-insulated feed line 4 and a similardraining line 5 to the refrigerating unit 6 (FIG. 1), which in this caseis designed as a condenser. Liquid refrigerant, for example Freon, ischannelled into the evaporator through the feed line, is evaporated in ameandering passage 10, connecting the feed line 4 to the draining line5, and as a result cools the cooling element to about -40° C. The vapouris led by the draining line 5 back to the refrigerating unit 6 and iscondensed there by heat extraction.

The condensate tray 7, arranged below the cooling element 3, has anouter shell 11 of steel, which is powder-coated on the outside, so thatit absorbs well there to prevent formation of condensation, and an innershell 12 of polyurethane or rockwool, or some other material of lowthermal conductivity, which is inserted into the outer shell 11. On theinside, it is provided with a lining 11a of reflective metal foil. Bythe construction described, cooling of the outside of the condensationtray 7 below the dew point is generally prevented. If these measures arenot sufficient, the outer shell 11 may be slightly heated. To facilitatedrainage of condensate, the condensate tray 7 is made to slope slightlytowards the discharge 8.

To facilitate the radiation exchange of the cooling element 3 with theroom 1 via the intermediate ceiling 9, the cooling apparatus is arrangedat a distance below the intermediate ceiling 9. The part of theintermediate ceiling 9 lying above the cooling element 3 is intenselycooled by radiation exchange with the cooling element and for its partcools the room 1 by radiation exchange. This effect is assisted by heatconduction in the intermediate ceiling 9. The radiation exchange withthe intermediate ceiling 9 may--at least in the initial phase of acooling phase when no ice layer has yet formed--be further intensifiedby the cooling element 3 being provided on the upper side with a coatingwhich absorbs well. By contrast, its underside, facing the condensatetray 7, is preferably reflective.

In the case of a second embodiment of the cooling apparatus (FIGS. 3a,b), the cooling element 3 is designed as a steel tube 13 bent in theshape of a U, through which brine cooled to about -40° C. in therefrigerating unit 6 (FIG. 1) is channelled. To intensify the radiationexchange with the intermediate ceiling 9, the steel tube 13 bears on theupper side a steel plate 14, to which it is welded. The steel plate maybe coated matt-black on the upper side to enhance the cooling effect.

The condensate tray 7 is of basically the same construction as describedin the first exemplary embodiment, but it maybe fastened on a pivotablespindle 15 extending parallel to its longitudinal axis, so that it canbe pivoted to the side through about 90° (arrow) out of its positionbelow the cooling element 3. The cooling element 3 is then exposed andcan enter into direct radiation exchange with objects in the room 1. Inthis way, a particularly intense cooling effect can be achieved, as maybe desired for example when cooling down an overheated room at thebeginning of a cooling phase. The edges of the condensate tray 7 arebent inwardly slightly, so that any residual condensate cannot run outduring pivoting of the tray.

According to a third embodiment of the cooling apparatus, the condensatetray 7 is designed as a flat dish of, for example, the shape of aspherical cup. The cooling element 3 is designed as part of a coppertube which is bent to form a double spiral 16 and, at the centre of thecondensate tray 7, merges into a heat-insulated feed line 4 and asimilar draining line 5, which are drawn into a further tube 17 made ofsheet steel. At the outer end, the double spiral 16 may be provided witha venting valve. The ends of the copper tube 16 are adjoined there, viatwo rapid action couplings 18, to two likewise heat-insulated hoses 19,which are led through the tube 17 into a hollow floor 21, situatedbetween a floor 20 and a concrete base (not shown), and are connected topermanently laid lines which establish the connection to therefrigerating unit 6 (FIG. 1) and carry brine or glycol as the coolingmedium. Likewise arranged at the centre of the condensate tray 7 is afilter 22, which adjoins by a discharge 8 for the melted-off waterresulting from the regeneration phase, and ends in a collecting tank 23.The condensate tray 7 is of basically the same construction as describedin the first exemplary embodiment. However, it additionally bears alighting element, a fluorescent tube 25, running around above areflector 24, for indirect illumination. Of course, additional lightingelements may be provided for direct illumination.

The tube 17, together with a base plate 26 surrounding it, forms a stand27, which bears the cooling element 3 and the condensate tray 7. Thebase plate 26 bears on the underside a base element 28, which can beused at various points of the floor 20, in that it replaces there anormal floor element, for example. Slightly above the base plate 26, thetube 17 has an opening 29, which can be closed by a cover and behindwhich the rapid action couplings 18 and the collecting tank 23 aresituated and can be accessed.

In the case of this configuration, it is very easily possible to movethe cooling apparatus elsewhere, by releasing the rapid action couplings18 and lifting the stand 27 with the floor element 28 out of the floor20 and replacing the element by a normal floor element. Subsequently,the cooling apparatus can be used at another point of the floor and beconnected again via the rapid action couplings 18 to heat-insulatedhoses, which establish the connection with permanently laid lines. Thisoffers the possibility of assigning a single cooling apparatus to oneworkplace, for example, and moving it, if need be, with the workplace aswell. It is then possible with comparatively low expenditure and, undercertain circumstances, significantly reduced energy consumption, toproduce a pleasant climate in the direct vicinity of the workplace,without it being necessary to cool the entire, possibly much larger,room. In the example described, a workplace light is integrated at thesame time into the cooling apparatus, designed in this way as aworkplace cooler. With the compact design of the cooling apparatus as aworkplace cooler, use is made in a particularly advantageous way of thehigh cooling capacity which the method according to the inventionoffers.

The design described can be modified in a wide variety of ways. Forinstance, instead of the collecting tank 23, there may be provided afurther rapid action coupling, which connects the discharge to a furtherhose and also to a condensate discharge provided in the hollow floor.

On the condensate tray there may be provided fixed and adjustablereflectors, arranged above the cooling element, or other deflectingelements for thermal radiation, for influencing the spatial distributionof the cooling effect, and possibly also deflecting elements for light.

A further modification is the use of an evaporator or Peltier elementinstead of the double spiral 16 as the cooling element. A Peltierelement makes it unnecessary--in particular when a collecting tank isbeing used for the melted-off water which then needs only to be emptiedoccasionally--for the feed line 4 and the draining line 5 for connectingthe cooling element to the refrigerating unit to be produced partly byhoses, and allows them instead to be formed entirely or partially ascables and to be connected by a plug connection, similar to anelectrical plug connection, to a suitable cooling installation, whichmay have, for example in each room, a heat exchanger, from which theheat generated by the Peltier element or plurality of Peltier elementsis abducted and transported to the refrigerating unit by means ofcooling medium. In this case, the stand may be provided with a flatbase, so that the cooling device can be moved around freely in the roomlike a standard lamp.

Although the use of a Peltier element as a cooling element isparticularly advantageous in the case of a moveable workplace cooler, itis of course also possible in the case of fixed cooling apparatuses.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered exemplary only, with a true scope and spirit ofthe invention being indicated by the following claims.

We claim:
 1. A method for climatically conditioning a room via radiantheat exchange, comprising:providing at least one cooling element inradiant heat exchange relation with the room to be conditioned; formingcondensate into ice on the cooling element during a cooling phase;maintaining the ice on the cooling element during the cooling phase toclimatically condition the room via radiant heat exchange between theice on the cooling element and the ambient air of the room beingconditioned; and subsequently melting the ice during a regenerationphase.
 2. The method of claim 1, further including alternating coolingphases with regeneration phases.
 3. The method of claim 1, whereincooling phases coincide to a great extent with times during which theclimatically conditioned room is in use.
 4. The method of claim 1,wherein regeneration phases generally coincide with times during whichthe room is not in use.
 5. The method of claim 1, wherein cooling phasescoincide to a great extent with times during which the climaticallyconditioned room is in use, and wherein regeneration phases generallycoincide with times during which the room is not in use.
 6. The methodof claim 1, wherein during a regeneration phase, any melted-offcondensate is caught and drained away.
 7. The method of claim 1, whereinduring a regeneration phase, the cooling element is switched off.
 8. Themethod of claim 1, wherein during a cooling phase, the temperature ofthe cooling element is set to a temperature no greater than -2° C. 9.The method of claim 1, wherein during a cooling phase, the temperatureof the cooling element is set to a temperature of approximately -40° C.10. The method of claim 1, wherein during a cooling phase, thetemperature of the cooling element is set to a temperature no greaterthan -5° C.
 11. The method of claim 1, wherein the cooling element isarranged in the ceiling area of the room to be cooled.
 12. The method ofclaim 11, wherein heat exchange between the cooling element and the roomto be cooled takes place predominantly by radiation exchange via surfaceareas arranged above the cooling element.
 13. The method of claim 1,wherein maintaining the ice includes maintaining the temperature of thecooling element to a temperature sufficiently low to freeze thecondensate formed on the cooling element during the cooling phase.
 14. Acooling apparatus for climatically conditioning a room via radiant heatexchange, comprising:at least one cooling element for radiant heatexchange with the room to be conditioned; and a refrigerating unit foralternating operation of the cooling element between a cooling phase anda regeneration phase, wherein cooling phases occur primarily when theroom to be conditioned is in use and regeneration phases occur primarilywhen the room to be conditioned is not in use; wherein during thecooling phase the temperature of the cooling element is set at atemperature sufficiently low to freeze any condensate formed on thecooling element and to maintain the frozen condensate as ice on thecooling element during the cooling phase, such that radiant heatexchange between the ice on the cooling element and the ambient air ofthe room being conditioned climatically conditions the room.
 15. Thecooling apparatus of claim 14, wherein during a regeneration phase thetemperature of the cooling element is set at a temperature sufficientlyhigh to melt off any condensate frozen to the cooling element.
 16. Thecooling apparatus of claim 14, wherein the refrigerating unit maintainsthe temperature of the cooling element at a temperature between about-5° C. and about -40° C. during the cooling phase.
 17. The coolingapparatus of claim 14, further including a condensate tray arrangedbelow the cooling element to catch and drain away condensate melted offthe cooling element during the regeneration phase.
 18. A coolingapparatus for climatically conditioning a room primarily by radiant heatexchange, comprising:at least one cooling element for radiant heatexchange with the room to be conditioned; a refrigerating unit forproviding a cooling phase operation by setting and maintaining thetemperature of the cooling element sufficiently low to freeze anycondensate formed on the cooling element; and a condensate tray arrangedbeneath the cooling element such that an inner surface of the condensatetray faces the cooling element, wherein the condensate tray includes aninner reflective surface, an outer absorbent surface for preventingcondensation formation, and an insulation layer between the inner andouter surfaces to thermally insulate the inner surface from the outersurface.
 19. The cooling apparatus of claim 18, wherein the condensatetray can be at least partially pivoted or pushed out of the area lyingvertically below the cooling element.
 20. The cooling apparatus of claim18, wherein the cooling element is connected to the refrigerating unitvia a feed line and a draining line which are at least partially of aflexible design.
 21. The cooling apparatus of claim 18, wherein thecooling element is designed as a tube, as an evaporator or as a Peltierelement.
 22. A cooling apparatus for climatically conditioning a room byradiant heat exchange, comprising:at least one cooling element forradiant heat exchange with the room to be climatically conditioned; arefrigerating unit for providing a cooling phase operation by settingand maintaining the temperature of the cooling element sufficiently lowto freeze any condensate formed on the cooling element; a condensatetray arranged beneath the cooling element such that an inside surface ofthe condensate tray faces the cooling element, wherein an outsidesurface of the condensate tray is thermally insulated from the insidesurface; and a floor-supported stand which supports both the at leastone cooling element and the condensate tray.
 23. The cooling apparatusof claim 22, wherein the outside of the condensate tray is of anabsorbent design.
 24. The cooling apparatus of claim 22, wherein theinside of the condensate tray is of a reflective design.
 25. The coolingapparatus of claim 22, wherein the cooling element is of an absorbentdesign on the upper side and a reflective design on the underside,facing the condensate tray.
 26. The cooling apparatus of claim 22,wherein the cooling element is connected to the refrigerating unit via afeed line and a draining line which are at least partially of a flexibledesign.
 27. The cooling apparatus of claim 22, wherein the coolingelement is designed as a tube, as an evaporator or as a Peltier element.28. A cooling apparatus for climatically conditioning a room by radiantheat exchange, comprising:at least one cooling element for cooling aroom by radiant heat exchange, wherein the cooling element is designedas a tube, as an evaporator, or as a Peltier element; partially flexiblefeed and drain lines for connecting the cooling element to arefrigerating unit, the refrigerating unit providing a cooling phaseoperation by setting and maintaining the temperature of the coolingelement sufficiently low to freeze any condensate formed on the coolingelement; and a condensate tray arranged beneath the cooling element suchthat an inside surface of the condensate tray faces the cooling element,wherein an outside surface of the condensate tray is thermally insulatedfrom the inside surface; and a floor-supported stand which supports boththe at least one cooling element and the condensate tray.